Method of molding embossed foamed polymethane laminates

ABSTRACT

THIS INVENTION RELATES TO THE PREPARATION OF LAMINATES USEFUL AS BUILDING BOARDS OR PANELS BY FORMING A FOAM WITHIN A MOLD WHICH HAS DECORATIVE FILMS RELEASABLY ADHERED TO THE MOLD SURFACE WHERE THE FOAM MATERIAL IS A   RIGID POLYURETHANE WHICH HAS SUBSTANTIAL IMPACT RESISTANCE.

M. T. CONGER May 28, 1974 METHOD OF MOLDING EMBOSSED FOAMED POLYMETHANE LAMINA'I'ES 2 Sheets-Sheet 1 Original Filed Sept. 23. 1968 m m m O T I k. I M m m w l.\' V F .\'T( )R. RVIN T. CONGER 1M4 mrormtv M. T. CONGER May '28, 1974 METHOD OF MOLDING EMBOSSED FOAMED POLYMETHANE LAMINATES Original Filed Sept. 25. 1968 2 Sheets-Sheet 2 RGTN T. Cousin av 7 ATTORNEY United States Patent 3,813,463 METHOD OF MOLDING EMBOSSED FOAMED POLYMETHANE LAMINATES Marvin T. Conger, Akron, Ohio, assignor to The Goodyear Tire & Rubber Company, Akron, Ohio Original application Sept. 23, 1968, Ser. No. 761,451, now Patent No. 3,630,819. Divided and this application July 29, 1971, Ser. No. 167,192

Int. Cl. B29d 27/04 US. Cl. 264-45 1 Claim ABSTRACT OF THE DISCLOSURE This invention relates to the preparation of laminates useful as building boards or panels by forming a foam within a mold which has decorative films releasably adhered to the mold surface where the foam material is a rigid polyurethane which has substantial impact resistance.

This application is a division of application Ser. No. 761,451, filed Sept. 23, 1968, now Pat. No. 3,630,819.

This invention generally relates to laminates useful as a building board or panel and the method of making the board, and more particularly, to a board and the method of making it of a foamed polyurethane resin having a decorative film cover.

Foamed synthetic resins, such as polyurethane, are known to have excellent insulating properties as well as excellent abrasion and wear resistance. These foams have been primarily used in the building field as fillers for building materials. Usually the building material, such an plywood, is used to form a sandwich with the foamed polyurethane resin. This sandwich construction took advantage of the excellent insulating properties of polyurethane foam resin. However, the plywood was necessary because the foamed polyurethane lacked the structural strength necessary to withstand the stresses it would encounter if used as the sole building material. Therefore, the prior building manufacturers use plywood or other building material to supply the necessary structural strength for the molded foam synthetic resins.

Polyurethane and other synthetic foam resins have been molded to form a wallboard. These molded foams, however, are brittle and as stated before, lack any degree of structural strength. These boards are not used, for example, as a curtain wall but are used mainly where strength and brittleness are not a factor, merely as an insulation wall covering in the manner plasterboard is used.

The present invention utilizes a laminate having a polyurethane foam core and a covering of a decorative film as a panel or building board which has the beneficial abrasion resistance, wear resistance and insulating properties of foamed synthetic resins and also has the necessary strength and rigidity to withstand some of the stresses encountered by load bearing building boards such as curtain walls.

It is therefore an object of the present invention to provide a laminate having a foamed core and a decorative film covering to withstand impact and compression and the method of making said laminate.

Another object of the present invention is to provide a decorative film covered polyurethane foam suitable for use as a building board which may be used as a curtain wall of a house or similar building structure or as a door.

A further object of this invention is to provide a method of obtaining a laminate having a shaped porous core which is formed and adhered to the film at the time the laminate is shaped.

Other objects and advantages of the present invention will be apparent from the following detailed description ice taken in conjunction with the accompanying figures of the drawings, wherein FIG. 1 is a plan view of a molding assembly, FIG. 2 is an enlarged perspective view of a mold having its lid open and FIG. 3 is a cross-section through the laminate. FIG. 4 is another embodiment showing a cross section mold standing upward in a vertical position and a movable pouring head above the mold.

Referring specifically to FIG. 1, numeral 3 represents a continuous endless conveyor system having various stages thereon for performing work on the mold. The mold 4 with the lid 5 open is shown on the conveyor system as it comes out of the mold temperature conditioning unit 6 and is stopped temporarily in station 7 to permit the film to be placed in the mold 4 and in the lid 5. The film is spread and adhered to the lid and the mold by placing a vacuum on the mold and lid by the vacuum means 8 including a vacuum pump, lines and flexible line with quick connector terminals. Thus, with the film spread out smoothly within the cavity of the mold body and the lid, the mold is moved past a foam pouring head 9 where sufficient foamable material is added to the mold to fill the mold when it has foamed. The mold moves from under the pouring head 9 and the lid is closed in station 10 just before the mold passes into and through the mold temperature adjusting means 11. As the mold leaves the heating means 11, the lid is opened within station 12 and the molded laminated article is removed from the mold and then the mold is cleaned prior to passing into the mold conditioning unit 6 to begin the next molding cycle.

Referring more specifically to FIG. 2 it will be noted that the molds are shown as essentially rectangular but other shapes including irregular can be used. Both the mold body and the lid have recesses therein sufficient to accommodate a laminated article of the desired size. For instance, where the mold is used to make a door the mold will be approximately 36 x 82 x 1% inches or the dimensions desired for appropriate panel or door. To facilitate the placing of the film within the mold and the lid, and getting the film properly adhered in these positions, it was found to be expedient to place an open woven fabric within the mold as this facilitates obtaining a vacuum over the entire surface of the mold body and the lid area. Thus, if we use an open weave fabric to facilitate placing or pulling the vacuum on the lid and/or mold, it will not be possible to obtain the characteristics in the film corresponding to those engraved on the mold. Therefore, an auxiliary means will be needed in this instance, to elfect or impart the proper embossing or other decorative effects on the finished laminate.

This can be readily achieved by placing an embossed breathable paper within the mold underneath the film and then pulling a vaccum on the mold to move the embossed paper and the film down within the mold cavity and the lid in the manner heretofore described. A further advantage of using embossed paper is that not only is the article or laminate produced having the desired embossing but the embossed paper may remain on the laminate to serve as a bulit-in protection or wrapping for the laminate during storage, shipping and its preparation for use. Thus, when the laminate is to be used the embossed paper may be removed to display the surface of the laminate without it being marred during shipping or storage.

The specific nature of this invention may be more readily understood by using a decorative film such as a polyester or a polyvinyl chloride film or other known films that have or can have impressed thereon the desired decorative effect. The nature of these decorative effects may vary widely but in general they comprise printing of a decorative design, such as the appearance of an oak, mahogany or walnut paneling, on the film and then the film is used to form the laminate. Also, the film can have thereon the desired design or surface features.

With the film held snuggly in place in the lid and/or the mold cavity by the vacuum, usually about 26 to 29 inches of mecury, then a polyurethane foamable reac tion mixture in an amount suflicient to fill the mold after foaming is added to the mold. Then the mold is closed and the foamable reaction mixture is allowed to foam and set. The rate of setting and curing of the foam may be enhanced by raising the temperature of the mold to about 100 to 200 'F. Usually in about to 20 minutes, depending on the temperature of the mold, the mold may be opened and the laminated article removed from the mold.

It should be appreciated that by adjusting the mold temperature relative to the temperature of the reaction mixture the skin of the foam or its outer layers can be controlled in density to thereby improve its impact resistance. Therefore, in some cases it is desirable that the mold be at least 10 F. cooler than the foamable mixture d to increase the density of the foam outward from the center of the mold to thereby improve its impact resistance.

It is desirable to trim off the excess film from the molded article to give it a finished appearance. If the laminated article has not been given a post heat cure, it is preferred that it rest in a flat position for several days and preferably about 7 days at about 70 F. to permit the foam to develop its optimum cure and physicals.

The present invention provides the building industry with a lightweight board or panel that can be used to construct a house, apartment building, motels and similar structures that can have excellent insulation properties. The boards and panels of the instant invention may be conveniently handled and rapidly installed by relatively few workers. As a result the over-all cost of the building is reduced. Reduction in cost, of course, is a major consideration in the highly competitive building industry.

In another embodiment the mold 13 in a vertical position as shown in FIG. 4 is moved preferably on a cart or dolly 14 to a pour station where the foamable mixture is poured from a movable pouring head 20 into the open topside 15 of the mold. Prior to the time the foamable mixture is added to the mold a decorative film 16, for example, of polyester or polyvinyl chloride, is placed in the mold and a vacuum pulled on the mold by vacuum lines 17 attached to fittings 18 in each of the upright parts of the mold. It should be noted that a loosely woven fabric 19 inside each half of the mold serves to distribute the vacuum over the inside of the mold and to hold the film 16 in the desired position inside the mold. As the foamable mixture 21 foams within the mold, it fills the mold. Therefore, the pouring openings 22 in the top of the mold are closed and the pressure on the inside of the mold will rise to 1 to or even 50 pounds per square inch. After the foam has set and cured and the pressure is dissipated through seam 23 of the mold, the mold is opened by unlocking the locking means such as clamps 24 distributed around the mold. Then the'hydraulic rams 25 are actuated to cause the two mold halves 26 and 27 to pivot about pivot points 28 and 2.9 to move the two mold parts to the open position so the molded article can be removed from the mold and more film can be placed therein to prepare the mold for the preparation of another article.

The foams suitable for use in this invention are produced by reacting a polyether glycol of about 700 to about 1500 and preferably 900 to 1500 molecular weight having incorporated therein about 30 to about 150 parts and preferably about 75 to 125 parts of suitable wood flour with an organic polyisocyanate that has a functionality greater than 2 with a suitable amount of a monomeric polyol, usually about 4 to 30 parts where polyol has .a I

urethane catalysts may be used to advantage to control the rate of reaction of the isocyanate with the polyether or the monomeric polyols and also to regulate the rate of foaming and curing of the resulting products.

Representative examples of the polyether diols that can be utilized are polypropylene ether diol, polybutylene ether diol and a mixed polypropylene-ethylene ether diol, or mixtures of these diols.

The monomeric polyols, preferably of 3 to 4 hydroxyl groups, that can be used in making the rigid polyurethane foams of this invention are those having a molecular weight less than about 500 and preferably less than 300 such as the following representative members: trimethylol propane, trirnethylol ethane, glycerine, hexane triol and N,N,N,N'-tetrakis-(Z-hydroxylpropyl) ethylene diamine. Since trimethylol propane is a solid it is advantageous to use it in conjunction with sufficient liqiud polyol such as glycerine to give a pumpable mixture and thereby facilitate the formation of the reaction mixture.

The wood flours useful in this invention are the nut or shell flours obtained by grinding up walnut and pecan shells and the shells or related nuts until they obtain a fineness of a powder and preferably sufficiently fine to pass through a 100-rnesh U.S. Standard Screen. These wood flours are preferably used in the amount of about 75 parts to about 125 parts per hundred parts of the polyether glycol.

The organic polyisocyanates useful in making the rigid foams of this invention are those which contain more than 2 and preferably about an average of 2.5 to 2.8 or more isocyanate groups per molecule of the mixture. A broad class of organic polyisocyanates suitable for use in this invention are those prepared from an aldehyde amine reaction product which has been phosgenated to give a polyisocyauate or mixtures of polyisocyanates. The preparation of isocyanates of this type is illustrated in U.S. Pat. No. 2,683,730. It should be appreciated that the methylene dilfphenylisocyanate) content of the mixture can range from about to about 10 percent by weight. Also, organic polyisocyanates such as tri(phenylene isocyanato) methane may be used. Normally, the amount of organic polyisocyanate used will be stoichiometrically calculated to give an NCO/ OH ratio of from about 0.9 to 1.15, or up to 1.3. A 1.1:1 ratio is preferred based on the polyether glycol used. The blowing agent may be water and can be used in about 0 to 5 parts per parts of polyether glycol provided an auxiliary blowing agent is present, at least when the water content is 0 percent. Also, the low boiling auxiliary blowing agents such as methylene chloride or the fluorinated hydrocarbons, for instance, di chloro difiuoroethane can be utilized to obtain a rigid foam having the desired characteristics with or without the use of water.

Representative examples of the many embodiments of this invention are set forth in the examples below where all parts are by weight unless otherwise designated. Although the examples use the one-shot method of producing the foam, it should be appreciated the two shot or other methods can be used, too.

EXAMPLE I A rigid polyurethane foam was prepared by preblending 22 parts of a polypropylene ether glycol of 1000 molecular weight, 3 parts of N,N,N,N'-tetrakis-(2-hydroxylpropyl) ethylene diamine, 1.5 parts glycerine, 1.5 parts trimethylol propane and 20 parts of walnut shell flour, 0.017 parts of dibutyl tin dilaurate, 0.1 parts dimethyl amino-2 methyl-l-propanol and 0.2. parts of water. These ingre dients were intimately mixed to give a component mixture A, then this component mixture A was blended and thoroughly mixed with 22 parts of a commercial oragnic polyisocyanate mixture having an average NCO value of about 2.8 and made by phosgenation of an acid rearranged product of the reaction product of formaldehyde and aniline.

This mixture was poured from the pouring head into a door mold 15 containing a plasticized polyvinyl chloride film in sufiicient amounts to fill the mold with foam. The mixture began to cream in about 30 seconds and the foaming filled the mold and set in about five minutes. The resulting foamed-in-place laminate was allowed to stand in the mold for to 12 hours at room temperature to attain a complete cure before being removed from the mold. This foamed laminate was hard and tough and could be nailed to wood in the normal manner to attach the foamed laminate to wood without the foam crushing or the nail pulling out. Thus, planular laminates having decorative facings were made.

EXAMPLE II Other foams that are used to mold laminated doors were made using the recipe shown in Table 1 by dispersing all the ingredients in the polypropylene ether glycol and then adding commercial organic polyisocyanate mixture, available under the trade name Mondur MR to eifect the formation of the foam. The resulting foam was poured into a suitable mold about 6 x 6' x inches containing a polyester film and allowed to foam and cure by standing at room temperature for three days. The products made using the recipes of Table l were then subjected to impact and deflection load tests. The results of these tests are recorded in Table 2 along with the density of the resulting foam:

TABLE 1.FORMULATIONS FOR DENSITY VARIATIONS lQuadrol is N,N,N,N-tetrakis-(2-hydroxyl propyl) ethylene dial MAMP is the abbreviation for dimethyl amino-2-methyl-1-propanol.

3 Mondur MB is a mixture of organic polyisocyanate having an average NCO content of about 2.7-2.8 supplied by Mobay Chemical Company.

Table 2 gives the results of the stiffness and impact tests performed on the above specimens. The stiffness tests were run by clamping a specimen 6 X l x Ms" so that a cantilever beam was formed. A load was applied so that the distance from the support to the load was 4%". The measurement taken was the load required, in grams, to deflect the beam Mt". The impact test was performed using a Gardner Impact tester. The impact, in inchpounds, at which first permanent damage to the specimen was observed, is recorded. In addition, the diameter of the cavity created by an impact of 30 inch-pounds is recorded. It should be noted that using lauan mahogany plywood facings in the same contraction, the first permanent damage was observed at less than one inch-pound and the diameter of the damaged cavity at 30 inch-pounds was .380 inches.

TABLE 2.EFFECT OF DENSITY ON STIFFNESS AND IMPACT These materials appeared to show rubbery type impact which accounts for the high impact properties of the doors.

EXAMPLE III Other foam recipes were used to form foamed laminates having a decorative film on its face. Some of these are shown in Table 3, where all the ingredients were premixed except the Mondur MR which was added at the time the foaming was desired. The cured foam samples made using the formulations of Table 3 were then subjected to impact and deflection load tests. The results of these tests are shown in Table 4.

TABLE 3.FORMULATIONS FOR SCROSSLINK DENSITY Resin 1010 is a polypropylene ether glycol of 1,000 molecular weight.

TABLE 4.EFFECT OF CROSSLINKING ON IMPACT AND S'IIFFNESS Impact Density First Diameter l4" deflec- (lbs./ damage cavity tion load cu. ft.) (in.-lbs.) (inches) (grams) In this specification films have been used to designate sheets of plastic, preferably of a thermoplastic or set nature, of about 3 to 30 mils thickness, for example, an ABS resin, polyurethane resin, pvc resin or vinyl resin, but metal foils such as aluminum, magnesium or alloys of commensurate thickness and flexibility, i.e. l to 10 mils, can also be used where they are formable or preformed to fit the mold. Also, sheets are used to designate a film which has either no design or a design thereon, with the design including printing, embossing or any of the other methods of imparting design to film.

The following tests were performed on the foamed laminated doors prepared according to the foregoing examples, using the following test procedures:

The Slam test was performed on a door slammer comprising a rigidly held frame into which a door is hung in a normal manner using commercially available hinges. A hole is drilled through the door to accommodate an eye-bolt at approximately the location of the knob. The eye-bolt was flexibly attached to a hydraulic cylinder device that pulled the door open and quickly released it. Attachment to the eye-bolt was by a length of rubber tubing. A spring was used to slam the door upon its release. A counter was provided to count the number of slams. One slam cycle required approximately 6 seconds.

The test was run continuously during which periodic checks were made on the condition of the door. Particular attention was given to the condition of the screws holding the hinges on the door. For these tests, 2 /2" No. 12 wood screws were used. Some commercially available doors have shown excessive damage in less than 50,000 hard slams.

The Racking test in the plane of the door was performed according to Federal Specification LLL-D-OOS 81. The door was supported rigidly on one edge in the slammer frame as in service and a 200 pound load was applied to the unsupported stile. Racking in the plane of the door shall not exceed 0.1 inch, and on removal of the load, permanent set shall not exceed 0.02 inches.

The Racking test perpendicular to the plane of the door was performed according to Federal Specification LLL- D-00581. The door was supported horizontally on two diagonally opposite corners. A load of pounds was applied to each of the other corners. A straight edge was laid diagonally across the two supported corners. Measurements were taken from the center of the door to the 'bottom of the straight edge. Racking in the plane of the door shall not exceed 3 inches at the center of the door and on removal of the load, the permanent set shall not exceed inch.

Due to the fact that the doors prepared according to this invention were somewhat thick in the center, it was difficult to obtain good measurements using a straight edge. An alternate method of measuring racking in the plane of the door was used. It consisted of measuring the change in the distance from the floor to the weighted corners due to the application of the load. By taking the average of the change of the two corners the results should approximate that of racking in the center of the door.

An additional racking test performed during this program was to check the racking perpendicular to the plane of the door over a 24 hour period. This is not required in the Federal specification, but since these doors were made from plastic materials, some knowledge of the creep properties was needed.

The Warp test was performed according to Federal Specification LLL-D-OGSSI. The door was placed in a horizontal position and the face was covered with wet cloth for 24 hours. After this period, the cover was removed and a straight edge was laid diagonally across the face of the door. The distance from the straight edge to the center of the door was measured. Warp for the door shall not exceed inches.

The Impact test was performed on a finished face of the door using a Gardner impact tester. A four pound Weight with a /8" ball point was used. The specimen was tested at 4 inch-pounds increments. The diameter of the indentation and the percent of break around the cavity were recorded.

Table 5 presents the results of Slam, Racking and Warping tests on doors made according to the foregoing examples which had a polyester film on the two planular faces.

TABLE 5.SLAM, BACK AND WARP TEST RESULTS Warp (in.)

Door No. 2 was installed in the slammer test frame. The top and center hinges were common door hinges while the bottom hinge was a bearing hinge. After 100,- 000 slams, the top hinge was showing some wear. After 134,000 slams the top hinge had worn A and the center hinge was showing some wear.

The test was terminated after 213,000 slams. Upon inspection, the door showed no sign of damage and the screws holding the hinges were tight. Both the top and center hinges showed considerable wear while the bottom hinge showed none. This indicates that hearing hinges should be used on all future slam tests.

In all of the 51am tests the door was in good condition when the test was terminated. After Door 4 had been removed from the test frame, it was discovered that one screw was missing from the bottom hinge and a second screw was loose. Upon investigation, it was found that these screws had been placed in an area of a cavity.

The racking tests perpendicular to the plane of the door are based on the alternate method of measuring described in the test procedures. For Door 4 both methods of measuring were used. The racking measured according to Federal Specification procedures was 22%,". This was 6" less than determined by the alternate procedure. The permanent set, 'by the Federal specification procedure, was 5 Obviously, there is some discrepancy between the two methods of determining racking, however, since Door 4 was tested by both procedures and was within the limits of the specification, it was satisfactory.

It should be pointed out thata Weyerhouser stave core door was tested in the racking test. It was slightly warped at the beginning of the test so that, when the straight edge was laid diagonally across the supported corners, one end was 3& off the corner. The racking by Federal specification procedures was A". However, by the alter: nate procedure, it was This shows that the test doors are considerably more flexible than the stave core door even though they are Within Federal specifications.

The 24 hours racking tests were performed to determine the amount of creep that can be expected from these doors. This is shown in Table 6 for Door 3.

TABLE 6.-CREEP IN DOOR 3 Corner 1 Corner 2 r measuremeasure- Time ment, in. ment, in. Back, in

$%u 8 /in 6% 6% 2% 4%: 24 hours 4% 4 i ls,

TABLE 7,-GARDNER IMPACT TEST Force (inchdbs) Hardboard Birch Door No. 4

4 Break, percent- None None None Cavity, d1a., ll'l $4 )4:

8 Break, pereent- None None None Cavity, d1a.,1n Vic 9510 at 12 Break, percent- 25 None 25 Cavity, dia., in %2 '96: A0

16 Break, percent 50 25 100 Cavity, dia., in- $4 862 1 A:

20 Break, percent..." 25 so 100 Cavity, dia., in--. as W:

24 Break, percent 75 50 100 Cavity, dia., in--. /15

28 Break, percent. 100 50 100 Cavity, dia., in... %2 "'/i6 32 Break, percent... 50 100 Cavity, dia., in 915 A0 36 Break, percent- 100 50 100 Cavity, dia., in %1 A0 While certain representative embodiments and details have been shown for the purpose of illustrating the invention, it will be apparent to those skilled in this art that various changes and modifications may be made therein without departing from the spirit or scope of the invention. V 7

What is claimed is:

1. In a method of preparing a foamed polyurethane laminate wherein a mold is releasably lined with a film of polyester or ABS resin or vinyl resin in the lower and lid portions thereof by a vacuum technique, sufficient polyurethane foamable reaction mixture is deposited in the mold to fill the mold when foamed, said mold being at least 10" F. cooler than the temperature of the foamable reaction mixture during foaming to give the foam an inhanced integral skin adhered to the film the lid of the mold is closed, the foamable mixture is allowed to foam and cure to adhere the film to the foam, the mold is opened and the shaped foamed laminate is removed, after the vacuum is released, the improvement comprising initially lining at least a portion of the said mold cavity with a breathable embossed paper to give the laminate the desired embossed effect.

References Cited UNITED STATES PATENTS Pincus et al. 264-45 Pincus et a]. 264-45 X Pincus et al. 26445 Pincus et a1. 264-45 Henrickson 26448 UX Dusel et a1. 264 45 Lee et a1. 264-45 X Frost 260-25 Robitschek et al. 161-161 McGregor 264-45 UX Johnson 264-45 Jennings 264293 X Fornwalt 264-293 X Graham et al. 264293 X Gould 264-45 Barkhuif et al. 264 45 Dusel et a1 264-90 X OTHER REFERENCES Dixon, 8.: Polyurethane Foam Moulding, in British Plastics, January 1963, pp. 24-27.

Alderfer, Sterling: One Shot Polyurethane Production, in Rubber Age, April 1963, p. 89-91.

Knox, R. E. and R. A. Stengard: Molding Rigid Urethane Foam, DuPont Bulletin: New Information About Urethane Foam Made With DuPont Hylene. Elastomcr Chemicals Dept, Oct. 28, 1960, pp. 1-12.

PHILIP E. ANDERSON, Primary Examiner US. Cl. X.R.

260-25 AK, 2.5 AZ; 26448, 54, 90, 293, DIG. 14, DIG. 17; 425-817. 

